Electric furnace.



Patented Maly H, 1918.

ffl/11111 "S lill marzian- APPUCATION PILU) JAN. 19H.

UNITED sTATEs PATENT oEEIoE.

HANS NATHUSIUS, OF FRIEDENSHTTE, KREIS BEUTHEN, GERMANY.

ELECTRIC FUBNACE.

Spcctcation of Letters Patent.

Patented May 14, 15H8.

Application tiled January 15. 1914. Serial No. 812,209.

either in a predetermined atmosphere or in lthe evacuated chamber,because heating by means of arcs by displaceable and regulatableelectrodes is completely avoided.

The heating b means of resistances is eected in art by the linin of thefurnace` ich s rammed onto t e electrodes, and in part by theVresistance which the charge in the furnaceioflers, in certain cases, tothe passage of tha current. It is conse. quently impo ible for thecharge to become impurified the material of the electrodes because thechargedoes not contact with the electrodes themselves.

The ,heating by radiation is effected by the liningiqof the furnaceheated by the resist ancesfparticularly when the furnace is onlypartiall filled with the char e.

The 'urnace is particular y intended for use in obtainin metallic zincfrom zinliiferrous ores on t e reduction method, and is characterized byonly such chemical and physical operations taking place in it as requrea lower temperature than that' of the electric arc. It is consequentlypossible entirely to obviate the employment of adjustable arc electrodeswhich necessitate in the masonry of the furnace, i. e. in the roof or inthe side walls, holes which can be closed only imperfectly, and it ispossible to shut oil' the atmospheric nir completely from the interiorof the furnace. The process can thusbe carried into practice as desiredeither under the action of the atmosphere-not'diluted by air or thelike-of a certain gas which is supplied from the outside or is producedduring the process itself, or as mentioned above in the evacuatedchamber.

The improved arrangement of the electrodes and the uniform distributionof curri-nt also guarantee the interior of the furnace being heateduniformly and, if desired, in a manner rcadilyregulatable.

The regulation of the heating is effected in this improved furnace, ifdesired during working, from the outside, t'. e. at the generator ortransformer by varyin the vo1tage at the electrodes by simple switchingoperations or by adjusting the rotatable part of a potential regulatoror by employing special auxiliary transformers formed as regulatingtransformers. Also, it can be effected by connecting in series with suchauxiliary transformers, which will then have a constant ratio oftransformation, a potential regulator or a special regulatingtransformer, or by connecting a regulating trans-` former or a potentialregulator in series with the main transformer or generator whichproduces at the electrodes a redetermned voltage which, in turn, isvaried by the apparatus connected in series. Lastly, the heatin in thisfurnace can also be regulated byma in the magnitude or phase of theadded vo tage directly dependent on the current sent into theelectrodes.

The Shape of the furnace resembles that of vertical or horizontalretorts heated heretofore by gas. The furnace preferably has the shapeof a lon vertical or horizontal chamber, e. g. of cy indrical form,which is completely lined inside with a mass, e. g Idolomite, whichconducts electricity when One illustrative embodiment ofm inyention isrepresented by way of example in the accompanying drawing, wherein Fgure1 is a lon tudinal section through a preferred form o my improvedfurnace.

Fig'. 2 is a-cross'section taken on the line a--b in Fig. 1, and

Fig. 3 is a 'diagram of connections.

Referring to the drawing, A designates the chamber of the furnace intowhose walls the electrodes E,. E2. E3, are built; they terminate inelgctrode plates P1. P2, P, Both the electrodes and their plates mayconsist of cast: steel for exam le. should embrace the interior of t efurnace as completely as possible. Th(` lining, through which thecurrent Hows and which 4is electrically heated. should be rammed aboutthe electrodesI and their plates. electrodes are connected in suchmanner to the source of current that a potential difierence existsbetween all-of them. so that the electric heating current flows betweenthe electrodes E1, EEa and the electrodes E., 110

They 10o The E and Ee and also between the electrodes 13 and E, and E2and E, and E, and E., and, in certain cases also from the one electrodeto the electrode of opposite sign diagonally opposite vit according tothe resistance conditions in the furnace.

It will be readily understood that an eX- ceedingly uniform distributionof. current and consequently a like distribution of heat can hereby beobtained.

In the illustrative embodiment three electrodes E1, E2, EB are arrangedatvthe one side of the furnace and theithree electrodes E, E5, Ee at theother side, each electrode being electrically connected with a source ofthree-phase current S, as shown in Fig. 3. Obviously, instead of usingthree electrodes at each sideonly two or four or more thereof may beemployed 'in like manner, according as two-phase, three-phase'or othermultidisposal.

phase current is at i desired todistil In the event of its being over orcondense vapors or gases the electrically heated chamber A is connectedby a passage r by one'or more flues with one or more receivers orvcondensers B which, in this illustrative embodiment, does not require tobe heated either electrically or otherwise.. If desired, this receiver Bcan be heated electrically in a manner 4analogous to that employed forthe'chamber' `Apr otherw'ise. by known means, e. g. by the gases fromthe chamber A.

The improved furnace can be geously employed whenever it is produce inthe furnace, 1s completely shut olf, or to which certain gases aresupplied to the perfectly closed chamber, a uniform temperature of aheight which is always below that obtainable by means of the electricare, such as is suitable for annealing, tempering, cementation and thelike of metal or iron bodies or for burnadvantadesired to in porcelain,bricks and like bodies or for' yco ing coal and obtainingby-products andin all similar cases.

1. A closed elec-tric furnace having a heating 4or reducing chamberwhosewalls 'are composed of electrically resistant material evbich iselectrically conductive when heatsaid wallsh aving xedly embeddedtherein in an air tight manner outsidethe chamber symmetrically disposedat opposite sides said sets of 'elec-.

of it sets of electrodes,

from which the airv trodcs embracing the chamber; and means forsupplying current to said electrodes.

2. A closed electric furnace having a heating or reducing chamber whosewalls are composed of electrically resistant material which iselectrically conductive when heated, said walls having fixedly embeddedtherein iu 'an air tight manner wholly outside the chamber andsymmetrically disposed at oppositesides of it, sets of elec trodes, saidsets of electrodes embracing the chamber; and means for supplyingcurrent to said electrodes in such a manner that a potentialdiiferenceexists between any two and all of the electrodes substantialbL asdescribed.

3. A closed electric furnace having aheatingor reducing chamber and asecond chamber Vcommunicating Awith the first mentioned chamber, thewalls of the heating or reducing chamber being composed of electricallyresistant material, which is electrically conductive when heated, saidwalls having fixedly embedded therein in an air tight manner entirelyoutside 'of the chamber and symmetrically. dis sed at opposite sides ofit sets of electro es, said sets of electrodes embracing the chamber;and means for supplying current to said electrodes 4in su'ch a mannerthat apotential di'erence exists be-` tween any twoand all of theelectrodes substantial] as described. .i

.4. A c osed4 electric furnace having a heating or reducing chamber anda second chamber communicating with the first mentioned chamber, thewalls of the heating or reducing chamber being composedof electricallyresistant material, which is electrically conductive wheny heated, saidwalls having lixedly embedded therein in an air tight manner entireloutside of the chamber and symmetrica ly disposed at opposite sides ofit setsof electrodes which terminate in electrode plates, said sets ofelectrodes a'nd -lates,.embraL-,ing the chamber; and means or supplyingcurrent to said electrodes in such a manner that a potential dierenceexists between any two and all of the electrodes substantially asdescribed.

- In testimony whereof, I aix my signature in the presence of twowitnesses. l .I HANS NATHUSIUS.

Witnesses:

vIlnNs'rKA'rz, ERNST Bnnvro'n

